Although integrity concepts for Global Navigation Satellite Systems (GNSS) are ubiquitous in the aviation
community, integrity algorithms of comparable maturity have not yet been developed for maritime users. The
International Maritime Organization (IMO) specifies requirements different from those specified by the
International Civil Aviation Organization (ICAO). These different requirements affect the design of the
integrity algorithms with respect to integrity risk allocation and threat space. This paper describes a novel
integrity algorithm based on conditions valid for maritime users. The performance of the novel integrity
algorithm has been assessed and compared to a conventional Receiver Autonomous Integrity Monitoring
(RAIM) approach consistent with IMO requirements.